1. Field of the Invention
The present invention relates to an air bag apparatus for absorbing the kinetic energy from a head portion of a vehicle occupant by inflating a bag body between a side of a vehicle body and the head portion of the vehicle occupant.
2. Description of the Related Art
A structure is suggested for an air bag apparatus which inflates a bag body between the side portion of a vehicle body and the head portion of a vehicle occupant so as to support the head portion of the vehicle occupant and absorbs the kinetic energy from the head portion of the vehicle occupant when sudden acceleration is applied to the side of a vehicle (International Publication No. WO93/09977).
This type of air bag apparatus is structured so that the bag body is arranged between the lower portion of a front pillar and a portion of the roof side close to a center pillar and an inflator communicating with the internal portion of the bag body is activated at the time of a side collision, thereby supplying pressurized gas to the internal portion of the bag body so that the bag body is inflated and expanded in a portion corresponding to the head portion of the vehicle occupant.
In the above-described air bag apparatus for absorbing the kinetic energy of the head portion of the vehicle occupant, a tube-like bag body received in a curved portion between the front pillar and the roof side is extended from a support point disposed below the front pillar to a support point disposed near the center pillar in the roof side so that an intermediate portion of the bag body having a long tubular shape is required to be set to position in a position corresponding to the head portion of the vehicle occupant.
Accordingly, in the conventional air bag apparatus, it is considered that an end portion of a connection strap disposed between an opening of a window and the bag body is fixed near one end portion of the tube-like bag body, the connection strap is drawn toward the support point of the roof side when the bag body is inflated and expanded, and the tube-like bag body is linearly extended from the support point of the front pillar to the support point of the roof side free of looseness.
In this case, when the bag body is inflated and expanded, the bag body is compressed by the connection strap against a force which rapidly inflates and expands the bag body generated by filling it with pressurized gas injected by the inflator. Accordingly, if the drawing motion of the connection strap is performed by using a portion of the gas injection energy of the inflator for inflating and expanding the bag body, since the connection strap is drawn by a strong force, the output of the inflator is required to be large so that the inflator becomes large and the manufacturing cost also rises.